In multi-feed weaving looms, a plurality of shuttles operate simultaneously, being moved while spaced apart from one another by the smallest possible distances. High weft-thread insertion performance is thus attained even at a relatively low shuttle speed. The short distances by which the shuttles follow one another necessitate a correspondingly short time sequence in supplying weft threads to the shuttles. In the case of shuttles operating with weft thread spools, a disproportionately great expense is required for constructing the shuttle supply means, which makes the utility of the entire multi-feed weaving loom uncertain.
In weaving looms with pneumatic insertion of the weft thread into the weft thread magazine of a particular shuttle (the magazine being embodied in the form of a chamber penetratable by air), it is possible with very simple technical means to attain a substantially better weft-thread insertion performance than would be the case if weft thread spools were used. The weft thread, measured out to a particular length, is then blown into the weft thread magazine by means of an injector through which a current of air flows. The length of the weft thread equals the width of the panel of fabric being woven, and the shuttle is supplied with a new weft thread between each two adjoining fabric panels.
The weft thread being introduced into the weft thread magazine of a shuttle is unwound from a cross wound spool or from a thread storage device located downstream of the spool. Ballooning of the thread then unavoidably occurs, being caused by the unwinding thread as it travels crosswise with respect to the direction in which thread is fed to the shuttle and thus intersects the air flow. Since air resistance increases with the square of the speed, the weft thread is subjected to severe strain, and its tear strength limits the speed with which it can be unwound.
In order to reduce the unwinding speed of the weft thread, it would be conceivable in principle to lengthen the weft thread magazine of an individual shuttle, in order to increase the length of time required for filling the weft thread magazine. However, this is not practicable,: since longer shuttles are then used, correspondingly fewer feed systems or shuttles can be accommodated in the weaving loom, so that the loom output would drop.
The invention:
It is accordingly an object of the invention to provide a method and apparatus for rapid supply of thread to the shuttles of a multi-feed weaving loom by pneumatic means, within a short distance shuttle movement path and with the correct weft thread for the intended fabric panel width, without thereby necessitating excessive strain on the weft thread or an extension in length of the weft thread magazine of the shuttles.
In accordance with, the invention, the injector, beginning at an outset position, is carried along with the shuttle at a slower speed for a predetermined distance while the weft thread is being introduced into the weft thread magazine. At the end of this distance the injector is rapidly brought back into its outset position.
There is a certain distance between the individual shuttles because of the shuttle stop and the changing of the shed. Because the injector is carried along with the shuttle while the weft thread is introduced into the weft thread magazine, the fill time available for introducing the weft thread is prolonged by the amount of time which a particular shuttle requires to traverse the distance corresponding to the distance between two adjacent shuttles. If, for instance, the injector is moved along with the shuttle at half the normal speed of the shuttle, and if the distance between two adjacent shuttles equals the length of one weft thread magazine, then the fill time is doubled; this has exactly the same effect as if the injector were stationary and the weft thread magazine of the shuttle were twice as long.
Basically, the difference in speeds of a particular shuttle and of the injector is determined such that there is no accumulation of the weft thread at one point in the weft thread magazine; instead, a uniform distribution of the weft thread in the weft thread magazine is attained. In order to utilize the entire length of the magazine, it is efficacious for the injector to be displaced relative to the shuttle by an amount corresponding to the length of the weft thread magazine while the weft thread is being inserted into the weft thread magazine.
In order to prevent the weft thread from being spun out of the injector as the injector is being rapidly returned to its outset position, it may be efficacious in certain cases for the weft thread to be laterally guided at least partially along its course to the injector; this may be accomplished, for instance, by having the travel path of the thread extend through a preferably transparent plastic tube or a plastic hose.
In producing woven goods containing various weft threads, at least two injectors can be used, each being assigned its own weft thread; one of the injectors is then moved out of the outset position along with the shuttle in order to insert the weft thread into the weft thread magazine, with the other injector or injectors either kept ineffective or rendered ineffective during this process. The result is very simple conditions in which the ineffective injector or injectors is or are held laterally beside the path of movement of the shuttles, and the injector which is to be moved with the shuttle is translated into the appropriate outset position for such a movement before the insertion of the weft thread into the weft thread magazine begins. The injectors may be selected according to a program, for instance, for insertion of the weft thread into the weft thread magazine in accordance with the desired color repeat. An electronic repeat control means may be used for this purpose.
The use of two injectors furthermore permits a further gain in time in filling the weft thread magazine of a particular shuttle. After the insertion of the weft thread into a weft thread magazine has ended, the injector requires a certain period of time for its return to the outset position; if only one injector is used, then this return time cannot be utilized for filling a weft thread magazine. However, if there are two injectors, then while the coupled injector is being returned following the insertion of the weft thread into the weft thread magazine, the second injector can be transferred into the outset position so that it can be carried along with the next subsequent shuttle. It is accordingly possible to begin inserting weft thread into the magazine of the next shuttle, immediately after the weft thread insertion into the first magazine has ended.
When the insertion of weft thread into the weft thread magazine has been completed, the weft thread is cut off at the edge of the fabric. It is particularly efficacious if the end of the weft thread is then automatically retracted into the injector as the injector is being returned to its outset position; this prevents its protrusion from the injector at the beginning of the loading of the next subsequent weft thread magazine, which could otherwise produce tangling and the like.
In accordance with further feature of the invention, the apparatus referred to above for performing the new method has the injector movably supported along a portion of the movement path of the respective shuttle and coupled with a driver mechanism, which is synchronized with the movement of the shuttle. By this driver mechanism, it is possible to impart to the injector a coupled movement with the shuttle which is effected at a predetermined speed-reduction ratio to the speed of the shuttle, at least during the process of insertion of the weft thread into the weft thread magazine of a particular shuttle and over a predetermined distance beginning at an outset position.
To this end, a sliding guide on which the injector is displaceably supported may be disposed in the vicinity of the movement path of the shuttle in one preferred practical form of embodiment. This sliding guide efficaciously comprises two parallel guide rails, between which the injector, having a fitted sliding piece, is guided.
With a view to the drive of the injector, the arrangement may be such that the driver mechanism has a coupler, which can automatically be brought into engagement with the injector as the latter is in its outset position; after the predetermined distance has been traversed by the injector, the coupler can be automatically uncoupled from the injector. The injector is coupled with a restoring device which then becomes effective and returns the injector to its outset position; the restoring device may have a restoring spring which is tensed during the course of the coupled movement of the injector.
Very simple and reliable structural conditions are attained if the coupler is disposed on a chain which has one stringer parallel to the path of movement of the injector and which is moved at the predetermined speed-reduction ratio to the movement of the shuttle. At the beginning and end of the movement path of the injector, this chain is guided over deflecting rollers, by means of which the coupler is movable toward the injector to engage it or away from the injector to disengage it.
The drive mechanism (that is, the chain) is efficaciously driven via a gear mechanism which engages a gear disposed on a portion of the shuttle drive which is moved in common with a particular shuttle.
In a preferred exemplary embodiment, a plurality of couplers is disposed on the chain, the distance between them being greater than the path of the injector by an amount which enables the return movement of the injector to its outset position. The length of time during which the injector is engaged by one of the couplers equals the fill time. As soon as the insertion procedure is ended, the coupler releases the injector, so that it can be rapidly retracted into its outset position; from there, it is moved synchronously along with the next subsequent shuttle, either by the same coupler of the chain or by the next subsequent coupler.
In order to assure that the severed end of the weft thread, as already noted above, will not protrude from the injector as the injector is being returned to its outset position, it is efficacious for a thread guide element to be disposed in the thread path taken by the weft thread toward the injector. By this means, the weft thread is held firmly, at the termination of its insertion into the weft thread magazine, at a point from which the thread path to the injector which has been returned to its outset position is longer than the path to the injector which has been carried along with the shuttle to the end of its own path.
As has also been noted above, the apparatus may have a plurality of injectors each of which is associated with its own weft thread; then each injector is capable of being coupled selectively with the driver mechanism. The injectors may be disposed beside one another at the side of the movement path of the shuttle, and one injector at a time can be translated by an adjusting device into the outset position for coupled movement.
If the apparatus includes a sliding guide having guide rails, then the injectors can each be disposed between two guide rails, while the guide rails themselves are adjustably supported transversely to the movement path of the shuttles. As soon as the weft thread insertion into a weft thread magazine has been completed and the magazine has left the injector, the guide rails are adjusted laterally, so that the now-ineffective injector can return unhindered to its outset position, while the injector intended for the next subsequent filling of a weft thread magazine assumes the outset position for its coupled movement and there comes into engagement with the driver mechanism.
When weft yarn whose strength permits a high thread unwinding speed is used, so that it is not necessary to prolong the fill time of the weft thread magazine, then the injectors may also be disposed in a register which is adjustably supported transversely to the path of shuttle movement. After a particular filling process, the register is displaced, during the interval until the next subsequent weft thread magazine is to be filled, such that the injector having the desired color of weft thread is brought into the outset position for coupled movement with the next subsequent shuttle. This adjustment of the register may be effected by way of example via a gear wheel drive which is automatically dependent on the movement of the shuttles in accordance with a program contained on a suitable program carrier, such as a punch card or a wiper chain or a memory element.
The injectors may also be preceded by an apparatus for measuring and supplying thread which has a continuously driven thread drum; the weft threads of the injectors can be pressed at intervals against the surface of this apparatus, this pressing movement of the individual pressure rollers being automatically dependent on the movement of the injectors.
Each injector is assigned its own pressure roller, which supplies the weft thread to the injector in accordance with a program. The axial length of the supply drum is dimensioned such that the required number of pressure rollers can come into action one beside the other.
As noted above, the described coupled movement of a particular injector with the shuttle while the weft thread is being inserted into its weft thread magazine prolongs the weft thread magazine fill time, as described; the desired prolongation is attained in accordance with the selected speed-reduction ratio between the shuttle and the coupled injector. However, if the weft thread unwinding speed is kept constant, then in the same manner the travel speed of the shuttles can be increased accordingly in comparison with conditions prevailing with a stationary injector; or another alternative as a comparison is the insertion of a double length of weft thread into the weft thread magazine, which makes it possible to produce correspondingly wider fabric panels with the same weft thread supply speed. In so doing, care should be taken that a correspondingly greater number of shuttles than be used for the fabric, and this likewise increases the loom output accordingly.